Modern motor vehicles increasingly incorporate amounts of non-ferrous metals. Aluminum, in particular, is finding increasing application because it combines high strength with low weight. Thus, manufacturing plants for engines, transmissions and other automotive components now commonly have to machine both ferrous metal and non-ferrous metal parts, thereby producing ferrous metal and non-ferrous metal chips.
Sound manufacturing practice calls for the recycling of waste metal. The recycling of aluminum has particular economic significance in view of the substantial amount of energy which is consumed in the production of aluminum.
Since substantially pure metals have much more economic value than mixed metal, it is important to be able to segregate ferrous metal chips from non-ferrous metal chips. One approach for accomplishing this has been to provide separate chip collecting and processing facilities for machine tools that produce ferrous metal parts and for those that produce non-ferrous metal parts. This, however, requires dual or duplicate coolant/lubricant collecting systems and chip filtration and processing systems. Such dual or duplicate systems both waste space and require an increased investment in plant and machinery, with a consequent adverse effect on manufacturing economics.
Attempts have also been made in the past to separate suspended ferrous metal particles from non-ferrous metal particles by using differential settling methods based upon the fact that ferrous metal particles, due to their generally higher density, will settle more rapidly than the lighter non-ferrous metal chips. Such methods, however, have not been effective to achieve the required degree of separation.
Another approach attempted in the prior art has involved collecting both ferrous metal and non-ferrous metal chips together, and then separating the ferrous metal chips from the non-ferrous metal chips, for example by magnetic separators. Such attempts have been less successful than desired because the magnetically collected ferrous metal chips tend to physically trap non-ferrous metal chips so that the desired degree of separation is not achieved.